The present invention relates to a front end assembly for an automobile vehicle and, more particularly, to a hydroformed tubular front end structure for use with unitized frame vehicles.
Conventional front end assemblies are often made by stamping and welding together several individual frame components. One of the major challenges for manufacturing is to maintain rigidity, improved geometric dimensional control and tighter tolerancing because these assemblies are often a combination of a number of various frame parts. As each of the frame parts are attached to form subassemblies and then are attached to the body portion of the vehicle, it becomes more difficult to achieve the necessary or desired stiffness while maintaining improved geometric dimensional control and tighter tolerancing in the front end.
Hydro-formed tubular elements are increasingly being used in the construction of vehicle body structures. Hydro-forming is a metal forming process that uses high-pressure fluids to outwardly expand tubular blanks to conform with the surfaces of a die cavity of a die assembly to form a contoured hydro-formed part.
Vehicle front end assembly processes have yet to take full advantage of the capabilities of tubular hydro-formed parts. A number of prior patents have described the use of tubular members in hybrid front end assemblies, but fail to address the matchboxing issue. For example, U.S. Pat. No. 6,416,119, granted on Jul. 9, 2002 to Dean Gericke, et al, describes a vehicle front end constructed through the use of hydro-formed tubes. In Gericke, a first body structure formed from a plurality of tube members and a second body structure formed from sheet metal are welded to each other in a sandwiching relationship. However, this method is still subject to matchboxing because the sheet metal structure can be distorted as it is secured to the tube members.
Other attempts at a tubular frame structure can be seen in U.S. Pat. No. 6,068,330, issued to Tatsuo Kasuga, et al, on May 30, 2000, in which the front end frame is formed by four members and is connected to tubular side frame members having internal ribs passing through the center axis thereof. Like Kasuga, the radiator supports are detachably mounted on front end frame members in U.S. Pat. No. 5,271,473, issued to Yoshinori Ikeda, et al, on Dec. 21, 1993. In U.S. Pat. No. 6,409,255, issued on Jun. 25, 2002, to Michael Tilsner, et al, tubular members are attached to the A-pillar to support the fender which is attached thereto by bolts.
Upper and lower frame rails are attached to a unitized frame in U.S. Pat. No. 4,573,734, issued to Gene Gass, et al, on Mar. 4, 1986. Modular frame components are disclosed in U.S. Pat. No. 4,900,083, issued to Hideyuki Kumasaka, et al, on Feb. 13, 1990, including the connection of longitudinally extending tubular members to the vehicle main body by a reinforcement. A tubular automotive frame apparatus is taught in U.S. Pat. No. 5,458,393, issued to Joseph Benedyk on Oct. 17, 1995.
There is a need for a front end construction that may incorporate the use of hydro-formed tubes that provides superior stiffness and rigidity when compared to conventional vehicle front end assembly designs. There is a further need for a front end assembly process that minimizes any tendency of the assembly to distort or matchbox. There is also a need to eliminate structural reinforcements, reduce part counts, and improve the durability of the vehicle body. Adaptation of a tubular front end structure to a unitized frame is desirable in order to reduce manufacturing cost, while retaining or improving crash performance characteristics. Furthermore, the utilization of tubular, hydroformed, front end components can facilitate the use of modules to be attached to the tubular members to further enhance manufacturing efficiencies.
Accordingly, it would be desirable to provide a tubular, hydroformed front end structure for automobiles that can be adapted for use in conjunction with unitized automotive frames.